Touch panels or touch screen panels are a particular class of electronic visual displays, which are able to detect and locate a touch within a display area. Generally, touch panels include a transparent body disposed over a screen and configured to sense a touch. Such a body is substantially transparent, so that light in the visible spectrum emitted by the screen can be transmitted there through. At least some known touch panels include a transparent body constituted by a barrier and a transparent conductor formed, in this order, over a substrate. A touch on the display area of such a panel generally results in a measurable change of capacitance in a region of the transparent body. The change in capacitance may be measured using different technologies, so that the position of the touch can be determined.
A transparent body for use with a touch panel is subject to some particular requirements. In particular, one key requirement is that the transparent body is stable enough for withstanding multiple contacts on the screen and harsh conditions, so that reliability of the touch screen is not compromised over time. However, at least some known transparent bodies included in touch screens, which are considered robust interfere with a proper transmission of light there through due to, for example, thickness, composition, and structure of the layers forming the transparent body. Furthermore, fabricating such a stable transparent body with high quality, for example with a uniform and defect-free barrier, is challenging.
Further, it is to be considered that there are different types of transparent bodies for touch panels. Particular consideration of the optical characteristics, e.g. the appearance to a user, has to be taken into account for transparent bodies, wherein the conductive layer for measuring the change in capacitance is a structured conductive layer.
A further aspect to be considered is a cost and material efficient solution for preventing the visibility or reducing the visibility of patterned portions of a touch panel. Thereby, particularly touch panels with integrated anti-reflection (AR) coating and/or anti-fingerprint (AF) coating are challenging because the AR coating and/or the AF coating increase the visibility of such patterned portions and can further develop over time, e.g. by abrasion of layers due to the use of the touch panel.
Accordingly, it is desirable to have a process and an apparatus for forming a high-quality transparent body for use in a touch panel in a manner such that the body is stably formed over the substrate without compromising a proper transmission, providing for touch sensor invisibility of light in the visible spectrum and reduced manufacturing costs.